Intermediate frequency transformer assembly



Aug. 4, 1953 R. A. LANG ErAL INTERMEDIATE FREQUENCY TRANSFORMER ASSEMBLY Filed July 17, 1951 .Wav M olwa, o

i etM A 7 Vw@ .w N, ,mmm m Patented Aug. 4, 1953 INTERMEDIATE FREQUENCY TRANSFORMER ASSEMBLY Robert A. Lang, Camillus, and Robert M. Savasky, Syracuse, N. Y., assignors to General Electric Compa/ny, a corporation of New York Application `l'uly 17, 1951, Serial No. 237,162

.l Claim. 1

This invention relates to intermediate frequency transformer assemblies particularly those which are tunable by means of adjustable iron cores. More particularly, my invention relates to such transformer assemblies having fixed-capacitor units including means for supporting the coil assemblies from the fixed-capacitor units.

Intermediate frequency transformers have long used a variable capacitor as the adjustable tuning member. Recently it has been found desirable variably to tune the transformer by means of adjustable iron cores positioned adjacent the coil assembly. In this arrangement the capacitor is fixed in nature.

While transformer assemblies employing fixedcapacitor units have been proposed, the method and means employed to assemble the transformers and in particular the capacitor base unit has proved unsatisfactory in several respects.

In the manufacture of such intermediate frequency transformers it is desirable to produce a -compact assembly which will achieve the desired result with a minimum of components, easily assembled, consistent with satisfactory performance. It has been found that in those intermediate frequency transformer assemblies employingl adjustable tuning slugs that the movement of such tuning slugs has tended to cause the insulating support for the coils to rotate with deleterious results. It is therefore desirable to produce intermediate frequency transformer assemblies in which the coil supporting members are securely attached to the fixedcapacitor base unit.

Further, it is desirable in such transformer .i

assemblies to employ a base unit in which the capacitive elements are secured therein in a simple yet efficient manner and in which heretofore used auxiliary compression members and now superfluous rivets are obviated.

It is therefore an object of this invention to provide an improved capacitor base unit for an intermediate frequency transformer.

It is another object of this invention to provide an improved fixed-capacitor base unit having improved means for supporting the insulating coil support member.

It is still a further object of this invention to provide an improved fixed-capacitor base unit for an intermediate frequency transformer assembly having improved means for securing the capacitive element within the base unit.

More specifically, it is an object of this invention to provide an improved intermediate frequency transformer assembly having improved means for xedly securing the coil support member to the fixed capacitor base unit and having, itself, improved means for securing the capacitive element within the base unit.

For additional objects and advantages and for fio a better understanding of my invention, attention is now directed to the following description and accompanying drawing. The features of this invention which are believed to be novel are particularly pointed out in the appended claim.

In the drawing:

Fig. l is a cross-sectional view of the improved intermediate frequency transformer assembly.

Fig. 2 is a perspective view of the improved transformer assembly shown in Fig. 1 with the shielding member and chassis removed.

Fig. 3 is an exploded perspective view of the transformer assembly shown in Fig. 2.

Referring to Figs. 1 and 2, I have shown an intermediate frequency transformer assembly I the general outline, function and operation of which are well known in the prior art. The assembly I includes a metallic shielding can 2 which may be secured to the -chassis 3 of any radio receiver or other translating apparatus employing such transformers by means of the U- shaped spring clip member 4. This clip member l! engages the metallic shielding can 2 through suitable apertures 5 therein.

Positioned within the metallic shield 2 is the coil assembly 6 which comprises an insulating cylindrical support member 'I upon which the coils and 9 are Wound. It will be understood that these coils are spaced apart according to known techniques imparting the desired inductance relationship therebetween.

The insulating coil support member I includes a plurality of spaced-apart vertically aligned notches I8 which are engaged by the threads of the adjustable core members II and I2 which are positioned within the cylindrical insulating support member l.

The cylindrical hollow insulating support member l is secured at its upper end within the offset portion I3 of the shielding envelope 2 and is secured at the lower end within the fixed-capacitor base unit I4.

The fixed-capacitor base unit I4, to be described in more detailed manner below and in connection with Fig. 3, generally includes a housing I5, a capacitive element I6 and a cover member Il.

Suitable apertures are provided for the admittance of tools to adjust the movable iron cores I and I2. Opening I8 is provided on the top offset portionv I 3 of themetallic shield 2 and a similar opening I9 is provided in the base unit I 4.

Terminal members 2li contact the capacitive element I6 Within the base unit I4 and are connected by suitable leads to the appropriate coils 8 and 9.

Referring now to Fig. 3, which is an exploded perspective view of the fixed-capacitor base unit I4, a plastic housing member includes a relatively thick bottom portion 22 and side walls 23-25.

The bottom 22 incorporates a centrally disposed aperture i9 through Awhich the tuning tool heretofore referred to may be inserted. This aperture I9 bears special attention in that the inner surface 2l generally tapers inwardly from thev top of the bottom portion 22 and includes .the key v portions 2S and 29. It is into this aperture I9 that the insulating coil support member 'l is inserted. The lower portion of theinsulating support member l includes keyways 30-3I which suitably engage the key portions 28-29of'the inner surface 2l. It will be i evident'that the tapered surface and keying action provide a convenient means for assuring that the support 'I will nt snugly within the-housing I and further that it will not move or rotate When'the iron slugs II andV l 2 are rotated therein.

The side wallsz.23.and'24 of the. housing I5 include grooved portions 32. The terminal members are adapted to be inserted'within' these grooved portions.

The. heretofore mentioned terminal members 2D areiL-shaped in configuration and comprise'a downwardly extending lead securing portion 33, having leadadmitting apertures 34 and a capacitor Contact making portion 35 which engages the capacitive element I6 located within'the housing.

The capacitive element I6 may comprise a sheet 3S of' insulating material such as mica having a conducting Amaterial 38'coated on opposite sides thereof. The mica insulating member 36, suitably silveredr incorporatesa centrally disposed'aperture I9 :large enough to'admt the insulating support member 'I when positioned withinzthe housing.

The cover andsecuring member I'I is composed of plastic material and includes a central aperture similar to that described inconnection with the capacitive element. This cover member I'I ts Within the plastic-base or housing member I 5. When the terminal members 2'and `capacitive element I6 are suitably secured within the housing member I5, this cover member. I7 -is fused to the housing I5 thereby' securing a'cornpact and easily assembled base .'unit. Although it may be fused along each edge, it is shown' fused at opposite edges 31.

For `purposes -of optimum fusion between the cover il and the housingl, bothl members may be composed of a similar plastic material. In our embodiment polystyrene has been employed. It will beunderstood that thisis by Way of illustration only and in no sense is to be considered a limitation.-

The intermediate frequency transformer assembly including the xed-capacitorbase unit may be assembled according to the following plan. First, suitable contact members 29 are positioned within the housing I5, the depending portion passingr through the grooved portionV 32. The capacitive element, havingtwo pairs of oppositely disposed silvered surfaces is then positioned on top of the two terminal members whereby each terminal rrember 29 contacts but one silvered area. Two other terminal members are then similarly positioned within the housing above the capacitor unit. The f plastic cover member II is then positioned on top of the capacitive element .I6 and terminals 20. The edges of the plastic cover I 'l and the upper edges of the side wall portions 23-4 of the housing are then subject to heat and/or pressure so as to fuse the cover member to the housing. It will be evident then that a compact base unit is thus provided which may be readily assembled and easily fastened together, obviating the need for any additional compression members or securing rivets.

The coil assembly S, comprising the cylindrical insulating support l, the spaced-apart coils 8 and Y S, and the adjustable tuning cores I I and I2, may

then be positioned so that the lower portion of the insulating support 1 having keyways 30 and 3I ts within the base unit I4. The key portions 28-29 `of the tapered surface 2T engage the key- Ways of the insulating support member 1. The lead connections ZI from the coils 8 and 9 may be then conveniently made to the terminal members 2G and the assembly enclosed by the metal can or shielding member 2. The lower portion of the shielding can 2 nts snugly around the fixedcapacitor base unit I4 and may include suitable tab portions (not shown) to fasten the shield to the housing. These tab portions may be of any desired configuration.

It' willv be apparent that more than one capacitor element may be provided within the base unit and that under certain circumstances, more than two coils may be positioned on the insulating support.

Thus, we have describedy an improved intermediate frequency transformer assembly Which facilitates the manufacture of such units by reducing the'number of required parts, by providing an improved fixed-capacitor base unit which incorporates a tapered opening and keyed portions adapted to engage and flXedly secure the insulating coil support member and further by providing an improved cover member which is fused to the plastic housing, forming aeompact unitary fixedcapacitor base unit.

While a specific embodiment of our invention has been shown and described and certain modifications have been suggested, it will of course be understood that various other modifications may be made without departing from the principles of the invention. The appended claim is therefore intended to cover any such modifications within the true spirit and scope of the invention.

Whatwe claim as new and novel and desire to be protected by United States Letters Patent is:

In a coil assembly, an insulating coil support member having a keyway at one end thereof, a iiXed-capacitor base unit comprisingan insulating plastic housing member having a bottom portion and sidewall portions, said bottom portion including a centrally disposed tapered aperture having a key portion adapted to engage said keyway of said coil support member, a fixed capacitor fitting within said housing and including a centrally disposed aperture, contact terminal members engaging said capacitor and a plastic cover member securing said capacitor within said housing member and having a centrally disposed aperture admitting said support member, said cover member being fused with said sidewalls at the respective edges thereof.

ROBERT A. LANG.

ROBERT M. SAVASKY.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date 1,982,411 Bailey Nov. 27, 1934 2,160,646 Contlee May 30, 1939 2,392,701 Sanders Jan. 8, 1946 2,435,639 Ketcham Feb. 10, 1948 

